Fetal hemoglobin and 2,3-BPG
Fetal hemoglobin has higher O2 affinity than adult hemoglobin mainly because it:
Answer B: explanation for every choice
A
Tighter 2,3-BPG binding would lower affinity.
B
Correct. Its γ chains bind 2,3-BPG weakly, shifting the curve left so O2 moves from maternal to fetal blood.
C
Both fetal and adult hemoglobin have four hemes.
D
Fetal hemoglobin still binds O2 cooperatively.
TakeawayFetal hemoglobin: weak 2,3-BPG binding → left shift → takes O2 from maternal blood.
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Reviewed 2026-11-05 by a medical student. Spot an error? Report it with question ID bb29.